nature 一篇文献的翻译《生物催化工程的第三次浪潮》

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bioengineering and translational medicine简介

bioengineering and translational medicine简介《Bioengineering & Translational Medicine》是一本专注于工程生物医学领域的学术期刊。

以下是关于该期刊的简要介绍：
- 该期刊由美国化学工程师协会（AlChE）于2016年创办，现为AlChE会刊，每年出版3期，现在由Wiley出版管理，期刊主编为哈佛大学的Samir Mitragotri 教授。

- 该期刊旨在及时、准确、全面地报道国内外工程生物医学工作者在该领域的科学研究等工作中取得的经验、科研成果、技术革新、学术动态等。

- 该期刊已被多个数据库收录，包括SCIE、BIOSIS Previews、STM Source、PubMed via PMC deposit (NLM)、Biotechnology Source等。

- 该期刊发表的文章类型以研究文章（Article）为主，同时也有综述（Review）、社论（Editorials）等。

- 该期刊主编Samir Mitragotri教授是美国哈佛大学的工程与应用科学教授，也是Bioengineering & Translational Medicine的期刊主编。

他是一位在药物靶向输送、生物医学材料、生物启发工程等领域有深入研究的科学家，已经撰写及合著了210余篇期刊论文，并拥有约150项专利。

总的来说，《Bioengineering & Translational Medicine》是一本在工程生物医学领域具有较高影响力和权威性的学术期刊，为该领域的科研工作者提供了重要的学术交流平台。

2020年在nature catalysis上发表重要成果

2020年在nature catalysis上发表重要成果
2020年，在《Nature Catalysis》杂志上发表了一项重要成果，该成果由某科研团队经过多年努力终于成功研发出一种新型的催化剂，能够有效地将废弃塑料转化为高附加值的产品。

这项成果的研发背景是，随着人类对塑料的依赖程度不断加深，废弃塑料的污染问题日益严重，给生态环境带来了巨大的压力。

因此，科研团队一直在寻找一种能够有效处理废弃塑料的方法。

该科研团队通过多年的研究，成功研发出这种新型催化剂。

该催化剂能够在常温常压下将废弃塑料中的聚乙烯和聚丙烯等塑料成分转化为燃料和化学品等高附加值的产品。

这种转化过程不仅能够有效处理废弃塑料，而且能够产生经济效益，具有很高的应用价值。

该成果的发表引起了广泛关注。

在《Nature Catalysis》杂志上，该论文被选为封面文章，并得到了编辑部的特别推荐。

该论文的发表不仅证明了该科研团队在催化剂研究方面的实力，也标志着人类在解决废弃塑料污染问题方面取得了重要进展。

未来，该科研团队将继续优化这种新型催化剂的制备工艺和应用范围，希望能够为解决全球废弃塑料污染问题做出更大的贡献。

同时，他们也希望通过与产业界的合作，将这种技术应用于实际生产中，为人类创造更加美好的生态环境和可持续发展未来。

nature catalysis decision sent to author 情况

nature catalysis decision sent to author 情况
摘要：
1.催化剂的定义和作用
2.Nature Catalysis 期刊的简介
3.论文投稿流程和决策过程
4.作者收到决策后的行动
正文：
催化剂是一种可以加速化学反应速率，但在反应结束后并不参与反应的物质。

在化学和工业领域中，催化剂起着至关重要的作用，它们可以使反应过程更高效、更环保、更经济。

Nature Catalysis 是一本专注于催化剂研究领域的顶级期刊，它致力于发表关于催化剂的理论和实验研究成果。

当一篇关于催化剂研究的论文投稿到Nature Catalysis 期刊后，编辑会对论文进行初步评估，以确定它是否符合期刊的发表标准。

如果论文通过了初步评估，它会被送到同行评审环节。

在这个环节中，至少两名专家会对论文进行深入评估，包括论文的研究方法、数据分析和结论等方面。

在专家评审完成后，Nature Catalysis 的编辑会根据专家的意见做出决策。

如果论文被接受，编辑会通知作者，并要求作者对论文进行一些必要的修改。

如果论文被拒绝，编辑会给出拒绝的原因，并建议作者将论文改进后投稿到其他合适的期刊。

当作者收到Nature Catalysis 的决策后，他们需要仔细阅读编辑和专家的意见，并对论文进行相应的修改。

如果论文被接受，作者需要按照期刊的要
求进行修改，并提交最终版本的论文。

海洋天然产物喹啉类生物碱的生物活性研究进展

化学鸟住够3終2021,-------------------------------------------------------综施专论―Chemistry&Bioengineeringdoi：10.3969/j.issn.1672-5425.2021.03.001李林拮，姚彤，毛联岗，等.海洋天然产物喳啡类生物碱的生物活性研究进展[J].化学与生物工程,2021,38(3):1-5,19.LI L Z,YAO T?MAO L G,et al.Research progress in biological activity of marine natural product quinoline alkaloids[J].Chemistry &-Bioengineering,2021,38(3)：1-5,19.海洋天然产物瞳咻类生物碱的生物活性研究进展李林詰1,姚彤3,毛联岗'，顾娜笃季春伟笃张珍明2，",李树安2"(1.江苏海洋大学海洋科学与水产学院，江苏连云港222005；2.江苏海洋大学环境与化学工程学院，江苏连云港222005；3.连云港杰瑞药业有限公司，江苏连云港222006；4.江苏省海洋资源开发研究院，江苏连云港222005)摘要：海洋天然产物摩咻类生物碱是从海洋生物中提取的次级代谢产物，具有新颖的化学结构和广谱的生物活性，是多种新药开发研制的先导化合物。

对海洋天然产物喳咻类生物碱的来源及生物活性进行了综述，并对其发展前景进行了展望。

关键词：海洋天然产物；喳咻类生物碱；生物活性中图分类号：0629.3文献标识码：A文章编号：1672-5425(2021)03-0001-05Research Progress in Biological Activity of Marine Natural Product Quinoline Alkaloids LI Linzhe1,YAO Tong3,MAO Liangang3,GU Na2,JI Chunwei2,ZHANG Zhenming24,LI Shuan24*(1.School of Marine Science and Fisheries^Jiangsu Ocean University^Lianyungang222005,CAzna；2.School of Environmental and Chemical Engineering9Jiangsu Ocean University,Lianyungang222005,C加na；3.J A RI Pharmaceutical Co.，Lul・，Lianyungang2220069China；4.Jiangsu Institute of MarineResources Development9Lianyungang222005^China)Abstract：Marine natural product quinoline alkaloids are secondary metabolites extracted from marine organisms9which are the leading compounds for the development of a variety of new drugs with novel chemical structures and broad-spectrum biological activities.In this paper,we review the sources and biological activities of marine natural product quinoline alkaloids?and put forward a prospect of their development.Keywords:marine natural product；quinoline alkaloids；biological activity嗟咻类化合物具有优良的药理活性，在医药化学、农药等领域应用广泛。

托夫勒的《第三次浪潮》

托夫勒的《第三次浪潮》编者按:近来报纸上一再出现“第三次浪潮”的说法。

这个概念是美国未来学家阿尔温・托夫勒首先在他的《第三次浪潮》一书中提出的。

所谓第三次浪潮是怎么回事?应当怎样认识它?本刊特发表《第三次浪潮》一书的摘编稿和《北京晚报》《人类的未来――乐观论析》一文，供读者参考。

人类的历史刚刚开始本书与悲观主义的观点截然不同，世界并没有面临末日，人类的历史才刚刚开始。

世界在混乱骚扰底下，蕴藏着惊人的希望和前景。

许多导致今天巨大危险的情况，也是打开未来大门的潜在的力量。

本书把人类文明分为三个时期:第一次浪潮农业阶段，第二次浪潮工业阶段，和目前正在开始的第三次浪潮。

探索未来社会的许多问题，是人类生存攸关的大事。

不论自己是否意识到，我们正在抵制或创造一个新文明。

本书将为读者作出自己的选择，提供帮助。

第一次浪潮历时数千年。

第二次浪潮至今不过三百年。

今天历史的发展速度更快，第三次浪潮可能只要几十年。

农业的兴起，是人类社会发展的头一个转折点。

工业革命，是第二次伟大的突破。

工业化在第二次世界大战后的十年，达到顶峰，第三次浪潮开始蜂拥而来。

在任何一个稳定的社会中，任何一个占优势的变革浪潮的发展前景，是比较容易看清楚的。

相反，当一个社会被两个或更多巨大变革所冲击，而没有一个显出优势时，对未来的信念就被弄得支离破碎，对变革的意义就难以辨明与选择。

两次浪潮之间的冲突，是以紧张的政局为中心，贯穿于今天的社会。

政治的根本问题在于:谁能为新文明的兴起作出规划，以取代旧的工业社会。

因为世界上许多严重问题，都不能在工业制度结构中解决了。

第三次浪潮技术的大变革我们又一次处于历史性的技术飞跃发展时期的边缘。

新的生产体系要求加速改建整个能源结构。

第三次浪潮能源结构的特点是:原料大部分是可以再生的，资源广泛，集中与分散相结合的生产方式，没有危险，浪费少。

能源问题的斗争，是与推翻第二次浪潮的技术交织在一起的。

二次世界大战后，英国工党所要求控制的工业“制高点”，恰恰是被技术革命所淘汰的煤矿、铁路和钢铁工业。

生物催化作业原文

Journal of Molecular Catalysis B:Enzymatic 65 (2010) 18–23Contents lists available at ScienceDirectJournal of Molecular Catalysis B:Enzymaticj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /m o l c a tbLipases for use in industrial biocatalysis:Speciﬁcity of selected structural groups of lipasesSangeeta Naik a ,∗,Aditya Basu a ,Rakhi Saikia a ,Bhawna Madan a ,Pritish Paul a ,Robin Chaterjee c ,Jesper Brask b ,Allan Svendsen baNovozymes South Asia Pvt.Ltd.,193,Hoody Circle,Whiteﬁeld Road,Bangalore,India bNovozymes A/S,Krogshoejvej 36,2880Bagsvaerd,Denmark cDepartment of Biochemistry at School of Biotechnology,Royal Institute of Technology,Stockholm,Swedena r t i c l e i n f o Article history:Available online 11 January 2010“Dedicated to Kalle Hult on his 65th birthday”.Keywords:LipaseBiocatalysisSubstrate speciﬁcity Enantio selectivitya b s t r a c tLipases for biocatalysisThe substrate speciﬁcity of a selected group of lipases was investigated.The enzymes selected were from four structural groups.Group 1:lipases having wide alcohol binding cleft but a narrow acyl binding cleft (Rhizomucor miehei lipase,Thermomyces lanuginosus lipase,Fusarium oxysporum lipase);Group 2:lipases which exhibit strong restriction on the acid part having a narrow tunnel to accommodate the acyl group but wider alcohol binding site (Candida antarctica A,Candida rugosa lipase);Group 3:lipases having wide acyl binding cleft but narrow alcohol binding cleft (C.antarctica lipase B,Ustilago maydis lipase),and Group 4:having wider alcohol and wider acyl binding clefts (Fusarium solani pisi cutinase,Humicola insolens cutinase).Owing to the wide substrate speciﬁcity and higher expression levels in recombinant host,these lipases have tremendous importance for hydrolysis and synthesis reactions.Various sub-strates with substitutions on the alcohol and/or the acid part of the ester molecule were selected.The experimental results support the classiﬁcation of lipases on the basis of their binding sites.For substrates with heavy alcohol side,C.Antarctica lipase A and R.miehei lipase type enzymes gave the highest extent of hydrolysis,while for acid heavy substrates the highest conversions were shown by C.antarctica lipase B.It is noteworthy that the acid heavy substrates which had aromatic side chains were hydrolyzed only by C.antarctica lipase B type of enzymes.Lipases were found to be more active on the alcohol-substituted substrates than acid-substituted substrates.© 2010 Elsevier B.V. All rights reserved.1.IntroductionOver the last few years,processes have been developed,using hydrolases,oxidoreductases or lyases as biocatalysts in phar-maceutical,agricultural,or synthetic organic chemistry industry.Lipases (triacylglycerol acyl hydrolases)exhibit wide substrate speciﬁcity,stereoselectivity and enantioselectivity and are there-fore,industrially signiﬁcant enzymes [1,2].The use of lipases in non-aqueous environments proves an excellent methodology for the preparation of single-isomer chiral drugs by enzymatic hydrolysis,transesteriﬁcation or aminolysis reactions.Applications of lipases in asymmetric synthesis include kinetic resolution of racemic alcohols,acids,esters or amines,as well as the desym-metrization of prochiral compounds [3–7].In the pharmaceutical industry,there has been an ever-increasing trend for chiral drug substances to focus enantiomers instead of racemic mixtures,∗Corresponding author.Tel.:+918030582171;fax:+918030582174.E-mail address:snai@ (S.Naik).A major part of the drugs manufactured today contains enan-tiopure molecules [8];hence,highly enantioselective reactions for the production of enantiopure building blocks are of great industrial importance.Enzymes are an attractive class of cata-lysts often used in the synthesis of enantiopure compounds.They usually exhibit high enantioselectivity,operate under mild reac-tion conditions and have a large substrate scope [9].However,with substrates that are very different from the natural sub-strate,enzymes can display low enantioselectivity and/or poor reactivity.A solution to this problem is to genetically modify the enzyme and thereby increase the substrate acceptance or enantioselectivity.Designing enantioselectivity of enzymes is one of the most attractive but challenging trials in the ﬁeld of protein engineer-ing for synthesis of enantiometically pure compounds,there is,however,no practical theory for introducing mutations into any enzyme to change its enantioselectivity.One way would be to model substrate lipases and esterases by substrate-imprinted dock-ing,which takes into account the substrate transition states,productive and non-productive hydrogen bonds as well as com-1381-1177/$–see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.molcatb.2010.01.002S.Naik et al./Journal of Molecular Catalysis B:Enzymatic65 (2010) 18–2319Table1Classiﬁcation of lipases on the basis of structural and physico-chemical properties of scissile fatty acid binding sites.Lipase class Group Active-site propertiesRmL type1Large alcohol binding cleft but a narrowacyl binding cleftCaLA type2Strong restriction on the acid part having anarrow tunnel to accommodate the acylgroup but wider alcohol binding siteCaLB type3Lipases having large acyl binding cleft butnarrow alcohol binding cleftCutinase type4Having wider alcohol and wider acylbinding cleftplete proteinﬂexibility.[10].Another approach would be to incorporate a desired enantioselectivity to enzymes by directed evolutionary strategy,which comprises iterative cycles of mutation and identiﬁcation of improved variants by screening or selec-tion[11–14].In one report,CaLA was made enantioselective for 4-nitrophenyl2-methylheptanoate,by using the CASTing(Com-binatorial active-site saturation test)[15],while another that the enantioselectivity of hydantoinase has been inverted towards D,L-5-(2-methylthioethyl)hydantoin by error-prone PCR and fol-lowing saturation mutagenesis[16],and enantioselectivity of a lipase from Pseudomonas aeruginosa was inverted by the combi-nation of error-prone PCR and DNA shufﬂing[17].Lipases have been classiﬁed on the basis of structural and physico-chemical properties of scissile fatty acid binding sites to understand the substrate speciﬁcity of lipases[18].In the current study,the substrate speciﬁcity of four structural groups of lipases (Table1):Group1:lipases having large alcohol binding cleft but a narrow acyl binding cleft(Rhizomucor miehei lipase(RmL),Ther-momyces lanuginosus lipase(TlL),Fusarium oxysporum lipase(FoL)); Group2:exhibit strong restriction on the acid part having a narrow tunnel to accommodate the acyl group but wider alcohol bind-ing site(Candida antarctica A(CaLA),Candida rugosa lipase(CrL)); Group3:lipases having large acyl binding cleft but narrow alcohol binding cleft(C.antarctica lipase B(CaLB),Ustilago maydis lipase (UmL)),and Group4:having wider alcohol and wider acyl binding cleft(Fusarium solani pisi cutinase(FsC),Humicola insolens cutinase (HiC))was investigated.The work presented here compares the substrate speciﬁcity of the various groups of lipases and also looks at the enantioselectivity of CaLB and some of its reported variants,M72L,T103G,and W104H [19].2.Experimental2.1.Strains,culture media and growth conditionsPichia.pastoris CoLS702[Mut−]strain(this strain is a deletion mutant of P.pastoris GS115strain,wherein the AOX1gene has been deleted)was used for heterologous expression of CaLA,CaLB, TlL,CrL-1,HiC and CaLB variants T103G,M72L and W104H.The strains were grown and maintained in YPD medium containing yeast extract(10g/l),peptone(20g/l),and dextrose(20g/l).For expression of the heterologous protein,the Pichia fermentation medium consisted of yeast extract(10g/l),peptone(20g/l),sor-bitol(10g/l),Potassium phosphate buffer(pH6.0,50mM),and yeast nitrogen base without ammonium sulphate and amino acids (3.4g/l).All fermentations were carried out in bafﬂed Erlenmeyer ﬂasks(1l)containing300ml of fermentation medium at27.5◦C and150rpm.The cells were induced after24h of growth with methanol(1%)and the temperature reduced to22◦C.Methanol induction was followed every24h for6days after which the cells were removed by centrifugation at12,000×g for25min,the super-natant wasﬁltered through0.2␮hollowﬁbreﬁlter and processed for puriﬁcation.2.2.Construction of expression plasmidsA P.pastoris vector CoLS789was used for the expression of CaLA, CaLB,TlL,CrL-1,HiC and CaLB variants T103G,M72L and W104H. This in-house vector has a HIS4selection marker,a multiple cloning site,the3 and5 sequences of a AOX1gene of P.pastoris and a pUC origin of replication.The genes with the native peptide signal were sub-cloned under the control of AOX1promoter.The resulting con-structs were used to transform Escherichia coli DH5␣.The plasmids were subjected to DNA sequencing for conﬁrming the sequence.2.3.Preparation of P.pastoris competent cells and transformationYPD100mL(1%(w/v)yeast extract,2%(w/v)peptone,2%(w/v) dextrose)medium was inoculated with a single P.pastoris colony and grown over night at30◦C,200rpm to an OD600of0.8–1.0. Cells were collected by centrifugation(10min,1500×g,and20◦C), washed with50ml of sterile water and suspended in2ml of 100mM LiCl2.The cells were washed twice with100mM LiCl2 and distributed in100␮l aliquots.To each cell aliquot was added 240␮L of PEG3350(50%),36␮L of LiCl2(1M),25␮L of single stranded DNA and50␮L of linearized plasmid DNA.The cells were mixed and were incubated at30◦C for30min without shaking and heat shock was given at42◦C for25min.The transformation mix was centrifuged and supernatant was discarded.The transformants were suspended in100␮L of sterile water spread on SD(Syn-thetic Dropout)plates(1.34%Yeast Nitrogen Base with ammonium sulphate without amino acids),4×10−5%(w/v)biotin,2%(w/v) dextrose)and incubated at30◦C for2–4days.The transformants were selected by their ability to synthesize and utilize histidine. 2.4.PuriﬁcationThe puriﬁcation methods for the various proteins are outlined below.Unless otherwise stated all columns used were of20ml col-umn volume(CV),and equilibration,washing and elution steps consisted to10CV buffer.2.4.1.CaLA and CaLBAmmonium sulphate(0.8M)was added to the fermentation broth and the broth passed through Butyl toyopearl hydropho-bic column which was previously equilibrated with Ammonium acetate(0.8M).The matrix was washed with equilibration buffer and the bound protein was eluted isocratically,ﬁrst with water and later with ethanol(50%).The eluted protein was dialyzed against HEPES(pH7.0,50mM)and passed through UnoQ(anion exchange). The unbound sample consisted of the puriﬁed protein which was concentrated using centrifugal concentrators and used for enzyme assay.2.4.2.TlLSodium chloride(2M)was added to the fermentation broth and the broth passed through Decyl agarose hydrophobic col-umn which had been previously equilibrated with sodium borate buffer(pH9.0,50mM).The matrix was washed with equilibration buffer and the bound protein was eluted isocratically with equi-libration buffer containing Isopropanol(30%).The eluted fraction were pooled,the conductivity was adjusted<7mS/cm and passed through Q-Sepharose(anion exchange)which had been previously equilibrated with sodium borate buffer(pH9.0,50mM).The matrix was washed with equilibration buffer and the bound protein was eluted using a linear gradient of sodium chloride(1M)in equilibra-20S.Naik et al./Journal of Molecular Catalysis B:Enzymatic65 (2010) 18–23Fig.1.The four selected structural classes of lipases.Representatives from each group oriented with superimposed active site.Active-site serine is shown in yellow,and with the acid binding part pointing upwards and the alcohol binding part pointing downwards.For the CrL the acid binding part is a deep tunnel going into the structure.Group 1;RmL (TlL:1GT6),Group 2;CaLA (CrL;1CrL),Group 3;CaLB (CaLB;1TCA),and Group 4;FsC (FsC;1CUS).tion buffer.The eluted protein was pooled,concentrated and used for enzyme assay.2.4.3.CrL-1Ammonium sulphate (0.8M)was added to the fermentation broth and the broth passed through Butyl toyopearl hydropho-bic column which was previously equilibrated with Ammonium acetate (0.8M).The matrix was washed with equilibration buffer and the bound protein was eluted isocratically ﬁrst with HEPES (pH 7.0,50mM)and later with HEPES (pH 7.0,50mM)contain-ing ethanol (50%).The eluted protein was dialyzed against HEPES (pH 7.0,50mM)and passed through UnoQ (anion exchange).The matrix was washed with equilibration buffer and the bound pro-tein was eluted using a linear gradient of sodium chloride (1M)in equilibration buffer.The eluted protein was pooled,concentrated and used for enzyme assay.2.5.Enzyme assaysThe activity of CaLA,CaLB,TlL,CrL-1,HiC and CaLB variants T103G,M72L and W104H were carried out in HEPES buffer (pH 7.050mM)containing CaCl 2(5mM)and Triton-X-100(0.4%).The reaction was started by the addition of substrate (40mM)and enzyme (0.1mg).All the reactions were performed at 30◦C for 2h,6h,or 24h to get appropriate conversion.The reactions were stopped with 100␮l HCl (1M)and the reactants extracted with dichloromethane.The organic phase (20␮l)was diluted with diethylether and analyzed on GC ﬁtted with chiral GC column (Var-ian CP-Chiralsil-DEX CB 10m).Two compounds,one from each substrate categories (A)sub-strates either branched/large on the alcohol part or (B)substrates either branched/large on the acid part were checked for enantiose-lective degradation of chiral isomers.The separation procedure for the two isomers on GC is outlined below.2-ethyl hexyl acetate:Oven T 1=70◦C,T 2=80◦C ( T =1◦C/min),T 3=90◦C ( T =2◦C/min),T 4=150◦C ( T =10◦C/min);Injector T =220◦C;Detector T =250◦C.Carrier N 2,ﬂow rate =0.5ml/min.Ethyl-2-methyl butyrate:Oven T 1=40◦C for 2min,T 2=52◦C ( T =2◦C/min),T 3=150◦C ( T =20◦C/min),Injector T =220◦C;Detector T =250◦C.Carrier N 2,ﬂow rate =1ml/min.Enantioselectivity (E )was calculated using below Equation.The activity is given as percentage conversion of the total amount sub-strate.E =ln {ee p (1−ee s )/(ee s +ee p )}ln {ee p (1+ee s )/(ee s +ee p )}3.Results and discussionLipases have been of signiﬁcant interest because of their wide substrate speciﬁcity.In this study,the speciﬁcity of lipases belonging to four structural groups (Table 1)has been exploited over a range of substrates based on the substrate site bind-ing geometry.Fig.1illustrates the four structural classes in this paper.The structural geometry of the lipase is the ﬁrst indication on the substrate binding possibility in the speciﬁc lipase type.Hydrogen bonding,van der Waals contacts and elec-trostatic interactions are the second important factors for the binding possibility.The X-ray structures indicate the potential main structural appearance of the enzyme under activated and inactivated conditions,respectively.In the present work the X-ray structures in the so-called “open”forms are used.For the practical measurements the structural forms may be dif-ferent and of course more dynamic,and for the lipases with lids and ﬂaps which need activation (like TlL,RmL,FoL,CrL,etc.)the experimental conditions have special impact on the binding of substrate to the enzyme.The assay condition has thus been focused to work with both lipases that need activa-tion (CaLA)and those that need little or no activation (FsC and CaLB).In accordance with the above hypothesis,two categories of substrates i.e.fatty acid esters were selected (A)substrates either branched/large on the alcohol part or (B)substrates either branched/large on the acid part.Examples included in ﬁrst category substrates—Isobutyl propionate,Styrallyl butyrate,2-ethyl-hexyl acetate and Cyclohexyl acetate.Examples included in the second category substrates—Ethyl-2-methyl butyrate,Ethyl-2-ethyl-hexanoate,Ethyl benzoate and ethyl-2-phenylpropionate.One of these substrates –ethyl-2-phenylpropionate is shown in Fig.2,which shows how the substrate –a profen core [20]–docks in a substrate binding pocket of CaLB (Fig.2).Most of the enzymes accept group “A”substrates,however,CaLA type enzymes,which are capable of accepting large alcohol groups,show highest activity.CaLB on the other hand is more strin-gent with respect to alpha carbon branching on the alcohol side as shown by its activity on styrallyl butyrate (Fig.3A).2-ethylhexyl acetate was chosen as a representative substrate for category A substrate and the enantioselectivity of all four groups of enzymes was checked this compound.Most of the enzymes except CaLB could not distinguish between the enantiomers (Fig.4).Docking studies (not shown here)showed that the different enan-tiomers bind in a similar fashion,which makes it hard for theS.Naik et al./Journal of Molecular Catalysis B:Enzymatic65 (2010) 18–2321Fig.2.(A)The acid and alcohol part of the substrate.(B)A profen core compound docked in the active site of CaLB.Fig.3.Enzyme activity on“branched”/“large”substrates on alcohol part(A)and acid part(B).The activity is given in conversion percentage of total amount substrate.Two conditions were chosen:Triton0,1%or Acetone5%,Buffer:50mM Tris-buffer,pH7,Amount of enzyme:0,5mg,Substrate volume:50␮l,All the reactions were performed in 30◦C and24h.The reactions were stopped with100␮l1M HCl and the reactants are extracted with dichloromethane.20␮l of the organic phase was diluted with diethylether and put on the GC.22S.Naik et al./Journal of Molecular Catalysis B:Enzymatic65 (2010) 18–23Fig.3.(Continued ).enzyme to experience any difference.This is probably due to the negligible size differences of the substituents in the branch-ing.CaLB showed very high enantioselectivity on 2-ethyl hexyl acetate.Therefore,it was decided to check the enantioselectivity of CaLB variants T103G,M72L and W104H [19]on the same sub-strate.The CaLB variant T103G which introduced the consensus mutation G-X-S-X-G in CaLB,thereby increasing thermostabil-ity,has shown reduced enantioselectivity towards 2-ethyl hexyl acetate (Fig.4).The CaLB variant W104H in which more space is introduced into the active site has shown 6.7-fold increase in enantioselectivity (Fig.4).The CaLB variant M72L having higher oxidation stability has also shown decrease in the enantioselectiv-ity (Fig.4).In group B substrates,ethyl-2-methyl butyrate was easily hydrolyzed by most of the enzymes (Fig.3B).The analysis based on molecular docking of CrL and TlL with this substrate showed that the R-enantiomer docked in an active fashion while the S docked with the oxygen orientated in the wrong direc-tion.This has also been shown by the results in which CaLA is showing better enantioselectivity than all the other groups (Fig.4).The hydrolysis of all other substrates was enzyme speciﬁc.RmL was the only enzyme which was capable of hydrolyzing Ethyl 2-ethylhexanoate (larger branch on acid part)(Fig.3B).This is prob-ably due to the large hydrophobic area of the active site of the RmL.Ethyl benzoate which had benzene ring on acid part was hydrolyzed only by CrL,TlL and CaLB (Fig.3B)whereas phenyl propionic acid ethyl ester having profen core structure was hydrolyzed only by enzymes in the CaLB group (Fig.3B).In conclusion,lipases are found to be more active on the alcohol branched substrates than acid-branched substrates.As depicted in the ﬁgures,for alcohol side large substrates,CaLA and RmL type enzymes give the highest extent of hydrolysis,while for large acid substrates the highest conversion was shown by CaLB.It is note-S.Naik et al./Journal of Molecular Catalysis B:Enzymatic65 (2010) 18–2323Fig.4.Enantioselective ratio of CaLA,CaLB,CaLB(T103G),CaLB(M72L)and CaLB (W104H),HiC,TlL and CrL-1on2-ethyl hexyl acetate and Ethyl-2-methyl butyrate.worthy that the large acid substrates which had aromatic side chains were hydrolyzed only by CaLB type of enzymes.4.ConclusionsStructural space for acceptance of substrates of different shapes in lipases from the groups of RmL,CaLA,CaLB and Cutinase has been explored.The RmL group allows large alcohol part substrate,but more limited/narrow acyl binding cleft on the acid part.CaLA group exhibits strong restriction on the acid part having a narrow tunnel to accommodate the acyl group from the acid part of the substrate and a much wider space on the alcohol part allowing highly branched and large groups on the alcohol part.The CaLB group shows more space on the acid part and less on the alcohol part and with restriction on the branching at CA carbon.Cutinase group has a reasonable open space on both the alcohol and the acid part of the substrate.This structural understanding was tested with the8substrates giving an overall result pointing in the same direction as the structural understanding.References[1]K.E.Jaeger,T.Eggert,Curr.Opin.Biotechnol.13(2002)390–397.[2]M.T.Reetz,Curr.Opin.Chem.Biol.6(2002)145–150.[3]S.T.Chen,J.M.Fang,.Chem.62(1997)4349–4357.[4]T.Shibatani,K.Omori,H.Akatsuka,E.Kawai,H.Matsumae,J.Mol.Catal.B.Enzym.10(2000)141–149.[5]H.Bernsmann,M.Gruner,P.Metz,Tetrahedron Lett.41(2000)7629–7633.[6]U.Ader,P.Andersch,M.Berger,U.Goergens,R.Seemayer,M.Schneider,PureAppl.Chem.64(1992)1165–1170.[7]V.Gotor-Fernandez,R.Brieva,V.Gotor,J.Mol.Catal.B Enzym.40(2006)111–120.[8]G.Beck,Synlett(2002)837–850.[9]O.Kirk,T.V.Borchert,C.C.Fuglsang,Curr.Opin.Biotechnol.13(2002)345–351.[10]P.B.Juhl,P.Trodler,S.Tyagi,J.Pleiss,BMC Struct.Biol.9(2009).[11]D.E.Robertson,B.A.Steer,Curr.Opin.Chem.Biol.8(2004)141–149.[12]P.A.Romero,F.H.Arnold,Nat.Rev.Mol.Cell Biol.10(2009)866–876.[13]M.J.Dougherty,F.H.Arnold,Curr.Opin.Biotechnol.20(2009)486–491.[14]J.D.Bloom, F.H.Arnold,A106(Suppl.1)(2009)9995–10000.[15]A.G.Sandstrom,K.Engstrom,J.Nyhlen,A.Kasrayan,J.E.Backvall,Protein Eng.Des.Sel.22(2009)413–420.[16]O.May,P.T.Nguyen,F.H.Arnold,Nat.Biotechnol.18(2000)317–320.[17]D.Zha,S.Wilensek,M.Hermes,E.J.Karl,M.T.Reetz,mun.(2001)2664–2665.[18]J.Pleiss,M.Fischer,R.D.Schmid,Chem.Phys.Lipids93(1998)67–80.[19]S.Patkar,J.Vind,E.Kelstrup,M.W.Christensen,A.Svendsen,K.Borch,O.Kirk,Chem.Phys.Lipids93(1998)95–101.[20]E.Henke,S.Schuster,H.Yang,U.T.Bornscheuer,Monatshefte fur Chemie131(2000)633–638.。

生命科学的第三次革命

⽣命科学的第三次⾰命苏珊·霍克菲尔德（SusanHockfield）⾃2004年12⽉起任⿇省理⼯学院第16任校长以来，直⼒倡导和推动科学技术以及研究型⼤学在世界事务中发挥重要作⽤霍克菲尔德1985年在耶鲁⼤学教授神经⽣物学，1994年被评正教授。

她在耶鲁⼤学度过了19春秋的学术⽣涯，曾经先后担任其研究⽣院院长、学校教务长、学术和⾏政主任等，在⼤学⾥发挥了核⼼领导作⽤。

霍克菲尔德致⼒于⼤脑发育和神经胶质瘤（⼀致命脑癌）的研究，在脑科学研究中开创了单克隆抗体技术的应⽤，并发现了⼀种在早期调节⼤脑神经元结构的蛋⽩质。

最近她发现了在⼤脑肿瘤扩散中起关键作⽤的⼀种基因及其产⽣的蛋⽩质家族，有可能成为脑胶质瘤靶向治疗的治疗靶点。

她在1973年获得美国罗切斯特⼤学(University of Rochester)的⽣物学学⼠。

1979年获得美国乔治城⼤学(Georgetown University)医学院的神经学博⼠。

1979⾄1980年为美国NIH的博⼠后研究员，1980年加盟美国纽约冷泉港实验室，1985⾄1997年任该实验室夏季神经⽣物学研究项⽬主任。

霍克菲尔德博⼠被布朗⼤学、清华⼤学以及沃森⽣物科学学院分别授予荣誉学位，并当选为美国艺术与科学院成员。

下⼀场创新⾰命来⾃⽣命科学、物理科学和⼯程科学领域内正在发⽣的历史性的⼤融合我很⾼兴能在此与⼤家相聚⼀堂，确实有⼀些值得我们庆贺的事情在发⽣。

美国总统奥巴马最近在美国科学院的讲话中对范围⼴泛的科学与⼯程学的价值坚定地给予了认可，我们不能将其视为⼀席空谈⽽⼀笑置之。

让我们摘引奥巴马总统讲话中的⼀段以共勉之：在⾦融危机的困难时刻，有⼈认为我们没有⼒量再投资于科学，在个钱要⽤在⼑⼝上的时期，⽀持科学研究在⼀定程度上是⼀种奢侈的花费。

但我本⼈完全不同意这种看法。

科学对于我们的繁荣、安全、健康、环境以及⽣活质量的意义，⽐以往任何时候都为重要。

当代研究生英语第七单元 B课文翻译

价格的利润生物公司正在吞噬可改变动物DNA序列的所有专利。

这是对阻碍医学研究发展的一种冲击。

木匠认为他们的贸易工具是理所当然的。

他们买木材和锤子后，他们可以使用木材和锤子去制作任何他们所选择的东西。

多年之后来自木材厂和工具储藏室的人并没有任何进展，也没有索要利润份额。

对于那些打造明日药物的科学家们来说，这种独立性是一种罕见的奢侈品。

发展或是发现这些生物技术贸易中的工具和稀有材料的公司，对那些其他也用这些工具和材料的人进行了严格的监控。

这些工具包括关键基因的DNA序列，人类、动物植物和一些病毒的基因的部分片段，例如，HIV,克隆细胞，酶，删除基因和用于快速扫描DNA样品的DNA 芯片。

为了将他们这些关键的资源得到手，医学研究人员进场不得不签署协议，这些协议可以制约他们如何使用这些资源或是保证发现这些的公司可以得到最终结果中的部分利益。

许多学者称这抑制了了解和治愈疾病的进程。

这些建议使Harold得到了警示，Harold是华盛顿附近的美国国家卫生研究院的院长，在同年早期，他建立了一个工作小组去调查此事。

由于他的提早的调查，下个月出就能发布初步的报告。

来自安阿伯密歇根大学的法律教授，该工作组的主席Rebecea Eisenberg说，她们的工作组已经听到了好多研究者的抱怨，在它们中有一份由美国联合大学技术管理组提交的重量级的卷宗。

为了帮助收集证据，NIH建立了一个网站，在这个网站上研究者们可以匿名举报一些案件，这些案件他们相信他们的工作已经被这些限制性许可证严重阻碍了。

迫使研究人员在出版之前需要将他们的手稿展示给公司的这一保密条款和协议是投诉中最常见的原因之一。

另一个问题是一些公司坚持保有自动许可证的权利，该许可证是有关利用他们物质所生产的任何未来将被发现的产品，并且这些赋予他们对任何利用他们的工具所赚取的利润的支配权利的条款也有保有的权利。

Eisenberg说：“如果你不得不签署了许多这样的条款的话，那真的是一个大麻烦”。

Three Gorges

中国的三峡大坝：是环境灾难吗？——甚至中国政府猜测大坝可能会造成严重的环境污染在上海，中国政府用了30多年的时间通过科学家和环境学家的论证已经解除警告：世界上最大的三峡大坝会成为中国最大的潜在的环境噩梦。

但是去年秋天，这种否认不得不让步于不情愿的接受。

中国官方立场大变，第一次承认，这个巨大的水力发电大坝被夹在中国中部扬子江变的悬崖中间，可能会引起山体滑坡，改变整个生态系统并引发其他严重的环境问题。

由此，危害生活在他周围的数百万生命。

政府官员一直在保卫这个240亿美元的项目，把它作为一个资源缺乏国家，可再生资源的主要来源，和预防下游洪水灾害的一种方法。

当工程完工的时候，这个大坝将会产生180亿瓦能量，是美国科罗拉河上胡佛大坝的8倍。

但在9月份，负责这个项目的政府官员承认，三峡大坝存在引发灾难的潜在的危险。

在重庆--一个与大坝邻接的约3100万人口的直辖市--的一次中国科学家和政府代表会议上，监督项目的代表国务院王晓峰表示，“我们不能掉以轻心”。

我们不能简单的以牺牲环境为代价来换取短期的经济效益。

这一评论似乎在承认，地理学家、生物学家和环境学家多年一直在警告大家的一个事实：建造一个在一个地区占有主要地位的巨大的水力发电大坝，它是威胁动植物物种的根源，并且，和地质断层线相交是产生灾难的关键原因。

乔治华盛顿大学医药研究中心的热带医学专家George Davis，24小时工作在长江流域及附近区域，他说,在这些破坏当中，包括“雨水减少了很多，干旱增加很多，疾病增加的可能性增多”。

一旦环境发生变化，三峡大坝及水库的运营将是所有变化的根本原因。

大坝型地震1992年，建三峡大坝的计划被批准时，人权运动者，就表示担心：为了给大坝的建设腾出空间，人们就被迫需要搬迁。

几千年来，三峡地区已经成为中国西部地区经济增长的主要部分。

迄今为止，政府已经安排集聚在长江岸边的2个城市、116个城镇的120万人口在工程开工前被疏散到其他地区，并承诺给他们几块土地和少量的生活补贴作为补偿，有些每月只给了50元或7美元。

nature catalysis 状态manuscript under consideration

nature catalysis 状态manuscript under consideration
我们非常高兴地宣布，我们的研究论文已经成功提交给了顶级期刊《Nature Catalysis》并进入了审稿阶段。

这是我们团队多年努力的成果，对于我们的研究能够在这个高影响力的期刊上得到展示感到非常兴奋。

这篇论文探讨了催化剂在化学反应中的关键作用，并提出了一种全新的催化剂设计方法。

我们通过使用先进的计算模拟方法和实验验证相结合的方式，成功开发出一种高效的催化剂，可用于加速某种重要的化学反应。

这项研究为解决环境和能源领域的挑战提供了新的策略和工具。

在这篇论文中，我们详细描述了催化剂的设计思路和研究方法，并提供了实验结果和计算模拟的详细数据。

我们的研究结果显示，新型催化剂在催化反应中表现出了出色的活性和选择性，比传统催化剂具有更高的效能。

此外，我们还通过对催化剂表面结构的调控，成功地实现了对反应过程的精确控制，进一步提高了反应的效率。

我们相信，这项研究对于催化化学和可持续发展领域都具有重要的意义。

催化剂的设计和优化是提高化学反应效率和减少能源消耗的关键步骤。

通过深入理解催化剂的工作原理和反应机制，我们可以开发出更高效、更可持续的催化剂，为未来的化学工业提供可持续发展的解
决方案。

我们对这篇论文能够引起《Nature Catalysis》编辑们的兴趣并进入审稿阶段感到非常荣幸。

我们期待着编辑们和同行专家们对我们的研究进行审稿，并提供宝贵的意见和建议。

我们相信，这篇论文将为催化化学领域的进展做出重要贡献，并推动新一代高性能催化剂的开发。

2013年考研外语阅读理解第三篇全文翻译

2013年考研外语阅读理解第三篇全文翻译注释：未来总是隐藏在迷雾中，借助已有的知识推测未来贯穿于整个已知的和我可以预见的人类文明史，尤其在工业化和信息化革命大幅度提升人类改造自然的能力并带来相当严重的后果之后，注重实证的西方科学体系甚至产生了过去干脆叫神棍的未来学。

人类的未来如何，甚至于人类能否存在到下个世纪甚至下个十年，争议一直不断，但我始终相信一点，在明天，在黑暗之后，太阳照常升起the sun rises as usual。

我在本文翻译中大量使用了意译，并在后面给出了直译，强烈提示，意译是一种很高的翻译技巧，按照考研判分的标准，如果采用意译，基本可以肯定是要么满分要么零分，如果自己的水平没有足够的把握，绝不要轻易使用。

Up until a few decades ago, our visions of the future were largely - though by no means uniformly - glowingly positive. Science and technology would cure all the ills of humanity, leading to lives offulfillment and opportunity for all.曾经，人类的未来似乎一片光明（意译，直译为前景辽阔，蒸蒸日上，只是发展各异）。

科技的发展必定能治愈顽疾，满足需求，提供契机。

Now utopia has grown unfashionable, as we have gained a deeper appreciation of the range of threats facing us, from asteroid strike to epidemic flu and to climate change. You might even be tempted to assume that humanity has little future to look forward to.然而如今梦想已成灰（utopia乌托邦，unfashionable过时的），我们要面对的是更可怕的现实，彗星撞地球、重度流感，甚至气候变更。

第三次科学范式转移

第三次科学范式转移原创 Kauffman等集智俱乐部导语科学的第一次重要转变被称为“牛顿范式”，牛顿发明了微积分和经典物理，教会了我们如何思考；第二次重要转变是20世纪初发现的量子力学和海森堡不确定性原理，是从经典到量子物理学的转变。

著名理论生物学家和复杂系统研究者考夫曼（Stuart A. Kauffman）等人认为，我们正面临科学的第三次范式转移，演化的生物圈是牛顿范式之外的世界。

生物圈是已知宇宙中最复杂的系统，我们不能用数学来推导预测生物圈的演化过程，一个不断演化的生物圈是一个自我构建的涌现过程，是涌现而非工程。

研究领域：复杂系统，自然演化，涌现，自上而下因果，科学范式转移Dialogue with nature ，译者小木球，审校目录摘要1.简介2. 生物圈不可推导式的历时演变（diachronic evolution）3.集合论不可逾越的极限4.第三次转型：我们已经超越了牛顿范式5.综合功能的演变：涌现不是工程6.结论摘要自牛顿以来，经典物理学和量子物理学都依赖于“牛顿范式”（Newtonian paradigm）。

“牛顿范式”系统的相关变量是确定的。

例如，当我们要确定经典粒子的位置和动量，需要先构建连接这些变量的微分形式的运动定律。

例如牛顿的三个运动定律，通过定义边界条件以创建所有可能变量的相空间。

然后，当给定了任意初始条件，对运动的微分方程做积分，就可以在预设的相空间中产生一个确定的轨迹。

牛顿范式的基本原则是，构成相空间的一系列可能性总是可以提前定义和确定的。

1.简介科学上的第一次重大转型可以归因于牛顿，他发明了微积分和经典物理。

毫不夸张地说，牛顿教会了我们如何思考。

因此我们将第一次重大转型称为“牛顿范式”（Newtonian paradigm）[3]。

（1）“牛顿范式”的第一步是，找到相关变量。

在物理学中，相关变量通常是位置和动量。

（2）写下这些相关变量的运动规则（laws of motion），通常是采用常微分方程或偏微分方程的形式。

Four Laws of Ecology中英对照

Four Laws of Ecology1 In broad outline,there are environmental cycles which govern the behavior of the three great global systems:the air,the water,and the soil.Within each of them live many thousands of different species of living things.Each species is suited to its particular environmental niche,and each,through its life processes,affects the physical and chemical properties of its immediate environment.1概括来讲,地球的三大系统—空气、水和土壤的行为由环境循环所决定。

每个系统中都生活着成千上万个不同物种的生物,每个物种都有与之相适宜的独特的环境生位,并且每一物种,在其整个生命历程中,都影响着它的周边环境的物理和化学特性。

2 Each living species is also linked to many others.These links are bewildering in their variety and marvelous in their intricate detail.An animal,such as a deer,may depend on plants for food;the plants depend on the action of soil bacteria for their nutrients;the bacteria in turn live on the organic wastes dropped by the animal on the soil.At the same time.the deer is food for the mountain lion. Insects may live on the juices of plants or gather pollen from their flowers.Other insects suck blood from animals.Bacteria may live on the internal tissues of animals and plants.Fungi degrade the bodies of dead plants and animals.All this,many times multiplied and organized species by species in intricate,precise relationships,makes up the vast network of life on the earth.2每个生物物种也与许多其他的物种相联系。

翻译

通过用碱金属盐修饰Ta3N5光催化剂提高水的氧化摘要氮化钽（Ta3N5）是一个具有良好应用前景的应用于光解水的氮化物半导体光催化剂，因为在可见光下(λ < 590 nm).，它具有能使水分解产生氢气和氧气的带边电位。

然而，Ta3N5的光催化行为远逊于人们对它的期望，因为其氧化物前驱体经热氮化法后结晶化的不足增加了不需要的电荷重组的可能性，从而限制了光催化反应的量子效率。

在本研究中，通过用少量的碱金属（AM）盐修饰前驱体Ta2O5表面，这个问题被成功地解决。

与传统方法合成的Ta3N5相比，用AM 盐修饰Ta2O5经氮化后得到的Ta3N5具有较好的结晶度和较小的表面较光滑的粒子，并且更重要的是，已经证明在可见光下，它提高了析O2的光催化活性6倍。

AM盐的修饰与加载析O2的助催化是相容的，如在500－600nm处，CoO x产生的表观量子效率为5.2%。

这表明，AM修饰的影响主要在于改变结晶度以及Ta3N5的形态，而不是影响催化剂。

对用Na2CO3修饰Ta3N5的细致的表征表明，在氮化的早期阶段，Ta2O5的部分分解和NaTaO3成核导致了粒子的特征形貌并且提高氮化物的结晶度。

本研究证明，对于初始物质简便的预处理可以提高大幅度地提高光催化剂的物理和光催化性质，使应用于光解水的先进的催化剂得到了发展。

正文光催化水解可能提供了一个经济可行的方法，这个方法是将太阳能直接转化为可再生并且可储存的氢气和氧气，因为水和日光是自然界丰富的资源。

由于它的简单性，用粉末状的光催化剂分解水已经激发了人们很大的兴趣，特别是可见光下就有光催化响应，这样可以有效利用太阳光。

对于通过分解水将太阳能转化，氮化钽（Ta3N5）是最具有前途的光催化剂之一，因为它具有2.1eV的带隙和合适的带边位置。

有报道说，在牺牲电子给予体或接受体分别存在的情况下，Ta3N5在可见光下使水分别产生氢气或氧气。

Ta3N5可以被用于析O2的光催化剂和作为Z型反应的光电阳极并且是水分解的光电化学。

新托福TPO9阅读原文及译文(三)The Arrival of Plant Life in Hawaii

新托福TPO9阅读原文(三):The Arrival of Plant Life in Hawaii新托福TPO9阅读原文(三):The Arrival of Plant Life in HawaiiWhen the Hawaiian Islands emerged from the sea as volcanoes, starting about five million years ago, they were far removed from other landmasses. Then, as blazing sunshine alternated with drenching rains, the harsh, barren surfaces of the black rocks slowly began to soften. Winds brought a variety of life-forms.Spores light enough to float on the breezes were carried thousands of miles from more ancient lands and deposited at random across the bare mountain flanks. A few of these spores found a toehold on the dark, forbidding rocks and grew and began to work their transformation upon the land. Lichens were probably the first successful flora. These are not single individual plants; each one is a symbiotic combination of an alga and a fungus. The algae capture the sun's energy by photosynthesis and store it in organic molecules. The fungi absorb moisture and mineral salts from the rocks, passing these on in waste products that nourish algae. It is significant that the earliest living things that built communities on these islands are examples of symbiosis, a phenomenon that depends upon the close cooperation of two or more forms of life and a principle that is very important in island communities.Lichens helped to speed the decomposition of the hard rock surfaces, preparing a soft bed of soil that was abundantly supplied with minerals that had been carried in the molten rock from the bowels of Earth. Now, other forms of life could take hold: ferns and mosses (two of the most ancient types of land plants) that flourish even in rock crevices. These plants propagate by producing spores–tiny fertilized cells that contain all the instructions for making a new plant–but the spore are unprotected by any outer coating and carry no supply of nutrient. Vast numbers of them fall on the ground beneath the mother plants. Sometimes they are carried farther afield by water or by wind. But only those few spores that settle down in very favorable locations can start new life; the vast majority fall on barren ground. By force of sheer numbers,however, the mosses and ferns reached Hawaii, survived, and multiplied. Some species developed great size, becoming tree ferns that even now grow in the Hawaiian forests.Many millions of years after ferns evolved (but long before the Hawaiian Islands were born from the sea), another kind of flora evolved on Earth: the seed-bearing plants. This was a wonderful biological invention. The seed has an outer coating that surrounds the genetic material of the new plant, and inside this covering is a concentrated supply of nutrients. Thus the seed’s chances of survival are greatly enhanced over those of the naked spore. One type of seed-bearing plant, the angiosperm, includes all forms of blooming vegetation. In the angiosperm the seeds are wrapped in an additional layer of covering. Some of these coats are hard–like the shell of a nut–for extra protection. Some are soft and tempting, like a peach or a cherry. In some angiosperms the seeds are equipped with gossamer wings, like the dandelion and milkweed seeds. These new characteristics offered better ways for the seed to move to new habitats. They could travel through the air, float in water, and lie dormant for many months.Plants with large, buoyant seeds—like coconuts—drift on ocean currents and are washed up on the shores. Remarkably resistant to the vicissitudes of ocean travel, they can survive prolonged immersion in saltwater when they come to rest on warm beaches and the conditions are favorable, the seed coats soften. Nourished by their imported supply of nutrients, the young plants push out their roots and establish their place in the sun.By means of these seeds, plants spread more widely to new locations, even to isolated islands like the Hawaiian archipelago, which lies more than 2,000 miles west of California and 3,500 miles east of Japan. The seeds of grasses, flowers, and blooming trees made the long trips to these islands. (Grasses are simple forms of angiosperms that bear their encapsulated seeds on long stalks.) In a surprisingly short time, angiosperms filled many of the land areas on Hawaii that had been bare.新托福TPO9阅读原文(三)译文：夏威夷植物的到来大约500万年以前，当夏威夷群岛作为火山从海洋中出现的时候，它们与其他大陆相距甚远。

新视野大学英语第三版B4U4 TextA 课文中英对照版

unit4 TextAAchieving sustainable environmentalism实现可持续性发展的环保主义1 Environmental sensitivity is now as required an attitude in polite society as is, say，belief in democracy or disapproval of plastic surgery。

But now that everyone from Ted Turner to George H. W. Bush has claimed love for Mother Earth, how are we to choose among the dozens of conflicting proposals，regulations and laws advanced by congressmen and constituents alike in the name of the environment? Clearly, not everything with an environmental claim is worth doing. How do we segregate the best options and consolidate our varying interests into a single，sound policy？在上流社会，对环境的敏感就如同信仰民主、反对整容一样，是一种不可或缺的态度。

然而,既然从泰德·特纳到乔治·W.H。

布什,每个人都声称自己热爱地球母亲，那么，在由议员、选民之类的人以环境名义而提出的众多的相互矛盾的提案、规章和法规中，我们又该如何做出选择呢?显而易见,并不是每一项冠以环境保护名义的事情都值得去做.我们怎样才能分离出最佳选择，并且把我们各自不同的兴趣统一在同一个合理的政策当中呢？2 There is a simple way。

英文文献翻译ppt

25℃下，不同乙烯压力通过催化剂所得的固体产物比较
结论
Turning a Cr-based heterogeneous ethylene polymerisation catalyst into a selective ethylene trimerisation catalyst
----将多相铬系聚乙烯催化剂转变成选择性乙烯三聚催化剂
摘要
keywords
催化剂活性测试
所有的催化剂测试都在悬浮液中进行，并且通过甲苯作为分散溶剂。两种装置参数需要被测试，第一中装置与工业生产条件紧密的结合（悬浮液系统、低压和高压、90℃），另外一个与均相复合物催化剂条件紧密结合（悬浮液系统、低压、 25℃）。所有实验的反应时间都是一个小时。CrCl3-TAC均相复合物在完全相同的反应条件并且使用相同的反应催化剂下被测试。低压实验的装置包括了一个具有天然橡胶塞和侧面旋塞连接着橡胶起泡器的玻璃反应容器。乙烯通过不锈钢针头由橡胶隔板不断地涌入。气体的出口则从起泡器连接着一个微小的气相色谱仪可以准确循环不断地分析气体的色谱图。乙烯气流速率被维持在30ml/min左右。起泡器被32-35ml的甲苯填满，反应器中加入25ml的甲苯，这两部都必须使用无水无氧甲苯，并且需要在手套箱里面进行操作。高压催化剂实验需要在压力达到11pa的金属反应器中进行。连续不断的乙烯原料被引入金属反应器中，以达到高压并且与反应压力平衡。为了评估催化剂的性能，催化剂材料的活性需要被0.04mmol的N，N-二甲基苯胺和等量的三异丁基铝激活。为了避免催化剂的减活性作用，所有的操作步骤必须小心谨慎。因此，都需要在无水无氧的条件下进行操作。反应的产物可以在液相中通过电子撞击GC-MS技术进行检测，例行的分析结果会被表示在Chromapack CP 9001气相色谱分析仪上。气相反应产物则通过Varian CP4900 micro-GC，以每两分钟一个样本注射的速度进行鉴别和分析。乙烯、1-丙烯、1-丁烯、1-戊烯、1-己烯的混合气体含量可由 micro-GC的刻度读出。

three pump-freeze–thaw cycle 原理

three pump-freeze–thaw cycle 原理1. 引言1.1 概述在现代科学技术发展的背景下，冻结-解冻循环作为一种有效的处理方法吸引了广泛的关注和研究。

其中，three pump-freeze–thaw cycle（三次泵冷冻-解冻循环）是一种被广泛应用于各个领域的技术。

该技术利用特定的冻结-解冻过程，在恰当的温度和时间条件下进行多次循环操作，从而实现对物质性能和品质的调控和改善。

1.2 文章结构本文主要对three pump-freeze–thaw cycle的原理进行深入研究和分析。

首先，将介绍冻结-解冻循环的基本概念，并详细阐述其中涉及到的关键步骤和原理。

其次，将探讨该技术在食品加工行业、医药领域及其他工业应用领域中所取得的成果和应用情况。

随后，会对其优缺点进行全面评估和分析。

最后，总结已有研究成果并展望未来该技术在不同领域中可能发展方向。

1.3 目的通过深入研究和分析，本文的主要目的是全面阐述three pump-freeze–thaw cycle的原理，讨论其应用领域，并对该技术的优缺点进行评估。

通过本文的撰写，旨在为相关研究人员和从业人员提供有关该技术的详尽信息，促进其在实际应用中得到更广泛和有效的推广。

同时，希望能够为未来相关领域的研究者提供借鉴与参考，以推动该技术取得更大的突破和进展。

2. 原理介绍：2.1 冻结-解冻循环概念：冻结-解冻循环是指物质在经历一系列的冷冻和解冻过程后所产生的效果。

这种循环可以改变物质的物化性质，并对其结构和性能带来明显影响。

通过多次进行冻结-解冻循环，可以使物质内部的水分析恒定渗透浓度，从而实现更好的品质和保存效果。

2.2 冷冻过程分析：在三次泵送-冷冻-解冻循环原理中，初次泵送是为了将待处理物质输送到制备设备中。

在此之后，物质被置于低温环境中，通过降低温度来实现快速冷冻。

在快速降温的过程中，水分会结晶并形成微小的晶体。

这些晶体会扩展并以不同方式排列，导致其他溶质和固体组分集聚在不同区域并形成相互作用。